Investigation into electrochemical catalytic properties and electronic structure of Mn doped SrCoO3 perovskite catalysts

Abstract

High activity, long lifetime and low-cost cathode catalyst plays an irreplaceable role in oxygen reduction reactions process. In the present work, SrCoO3 and SrCo0.875Mn0.125O3 perovskite are prepared by sol–gel method and first principles calculation to study the role of Mn doping. The characterizations of phase, microstructure and valence state of elements demonstrate that Mn doping stabilizes the cubic structure of SrCo0.875Mn0.125O3 perovskite and forms a porous structure with large specific surface area. The high-valence and multivalent states of Co and Mn are produced, which provide abundant active sites for oxygen reduction reaction. The charge transfer resistance (1.820 Ω·cm2), Tafel slope (88 mV dec−1), discharge capacity (4.173 mWh/cm2), and positive shift of onset potential and half-wave potentials reveal that the SrCo0.875Mn0.125O3 perovskite is a promising cathode catalyst. Mn doping helps the O p-band center move up relative to the Fermi level, and adsorption energy of O2 and formation energy of oxygen vacancies increase. The improvement of these parameters has a positive effect on predicting the catalytic activity of SrCo0.875Mn0.125O3 perovskite. The possible oxygen reduction reaction mechanism of SrCo0.875Mn0.125O3 perovskite is discussed. Mn doping accelerates the transport process of SrCo0.875Mn0.125O3 perovskite.